In this study I investigated the interactions of 25 Grade 8 science students as they learned how to construct oral arguments using the Toulmin Argumentation Pattern framework. I collected the data during three recorded small group discussion sessions during a five week Earth Science unit between February and March of 2011. The first session recorded the students’ discussions prior to receiving either argumentation instruction or the science concept instruction. The second session recorded their discussions after receiving an introduction to argumentation and a scaffold, but not concept instruction. During the three weeks preceding the third session, the students received additional argumentation instruction and completed one-third of the Earth Science unit. The results showed the students collectively made more arguments during each subsequent session. The students’ individual arguments showed a correspondence between their purportedly most familiar topics and the most discussed topics. I also found that when students made counter arguments and/or invited or challenged group members to participate, their discussions contained comparatively more argument elements (claims, data and warrants) than discussions containing predominantly collaborative assertions. The key outcome of this study for developing students’ use of the elements of argumentation during classroom discussions was to recognize and incorporate opportunities for the students to tap into their prior-knowledge. To engage students in this process, the results indicate the importance of creating time for discussions relevant to the curriculum and to the students. / Graduate / 0727 / 0279 / 0714 / brianu@uvic.ca